Method and apparatus for supporting P2P communication in TDD CDMA communication systems

ABSTRACT

A method performed by a network system is provided for canceling interference signals brought by introducing P2P communication in wireless communication systems, comprising: receiving a call request from a user equipment in a cell for communicating in UP-BASE STATION-DOWN mode; judging whether there is an appropriate link timeslot in the several available timeslots for the user equipment to avoid being interfered by P2P signals transmitted by the chosen user equipments allocated in the appropriate timeslot when the user equipment communicates in the appropriate timeslot, according to the relative position of the user equipment and the chosen user equipments in P2P communication in the cell; approving the call request from the user equipment and allocating the appropriate timeslot to the user equipment if the appropriate timeslot is available.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for supportingP2P communication in TDD CDMA(Time-Division-Duplex Code DivisionMultiple Access) communication systems, and more particularly, to amethod and apparatus for reducing signal interference caused to a UE(user equipment) during P2P communication process in TDD-SCDMAcommunication systems.

BACKGROUND ART OF THE INVENTION

In conventional cellular communication systems, a UE (user equipment)has to communicate with another UE only through the relaying of basestations regardless of the distance of the two communicating UEs. FIG. 1illustrates the conventional communication mode, wherein UE1 and UE2interact with each other through the UTRAN consisting of base stationtransceiver (namely Node B) and RNC, and this communication mode is alsocalled UP-UTRAN-DOWN mode. However, in some cases when the distancebetween two UEs who are camping in the same cell is very close, it canbe a more reasonable way for them to communicate directly, rather thanthrough the relaying of base stations. This method is the so-calledpeer-to-peer communication, abbr. as P2P.

FIG. 2 illustrates a P2P communication mode. As shown in FIG. 2, thedashed line represents signaling link, the solid line for data link, andthe arrowhead for direction of information flow. Only signaling linkexists between the UTRAN and the UE, while only data link exists betweenthe two communicating UEs. Let's suppose only resource for maintainingbasic communication is needed. If a direct link is taken as a radioresource unit (having fixed frequency, timeslot and spreading code), itcan be easily inferred that P2P communication mode only needs two radioresource units to maintain basic communication. If additional signalingcost for management is ignored, P2P communication can save about 50%radio resource than conventional communication mode. Furthermore, theUTRAN still holds control over P2P communication, especially over how touse radio resources, so wireless network operators can easily charge forthe radio resources used by P2P communication.

It is commonly accepted that a Time Division Duplex (TDD) air interfaceis a communication standard that offers a more flexible adaptation todifferent uplink and downlink traffic requirements. Among existing 3Gsystems based on TDD communication mode TD-SCDMA (TimeDivision—Synchronization Code Division Multiple Access) system is themost suitable system for the combination of P2P communication withconventional communication mode, because the same carrier frequency isapplied in both uplink and downlink communications, which can simplifythe RF (Radio Frequency) module of the UE.

A method and apparatus for establishing P2P communication in wirelesscommunication networks, as described in the patent application entitled“A Method and Apparatus for Establishing P2P Communication in WirelessCommunication Networks,” filed by KONINKLIJKE PHILIPS ELECTRONICS N.V.on Mar. 7, 2003, application Ser. No. 03119892.9, is suitable to any TDDCDMA communication system including TD-SCDMA systems, and incorporatedherein as reference.

A method and apparatus for radio link establishment and maintenance withP2P communication in wireless communication networks, as described inthe patent application entitled “A Method and Apparatus for Radio LinkEstablishment and Maintenance with P2P Communication in WirelessCommunication Networks,” filed by KONINKLIJKE PHILIPS ELECTRONICS N.V.on Mar. 7, 2003, application Ser. No. 03119895.3, is suitable to anywireless communication system including TD-SCDMA systems, andincorporated herein by reference.

After establishing uplink synchronization with the UTRAN through thesame random access procedure as existing TD-SCDMA systems, the UE canestablish P2P direct link with another UE, in accordance with the methodand apparatus as described in the application document whose applicationSer. No. is 03119892.9, i.e.: allocate relevant dedicated resource fortwo P2P UEs. Then, direct link between the two UEs can be establishedand maintained in accordance with the method and apparatus as describedin the application document whose application serial number is03119895.3, so that the two UEs can receive and transmit P2P signals inthe allocated timeslots respectively, and thus P2P communication betweentwo UEs can be implemented.

In a TD-SCDMA system capable of employing P2P communication mode, DIRECTmode is introduced to describe the direct communication between two UEs,besides two other working modes—IDLE mode and CONNECT mode as defined inconventional TD-SCDMA system. The communication link in direct mode canbe defined as FORWARD link (e.g.: the link from UE1 to UE2) and BACKWARDlink (e.g.: the link from UE2 to UE1) identified by the information flowdirection for one UE to send signals to the other UE or receive signalsfrom the other UE. Because P2P communication mode is built incombination with existing TD-SCDMA systems, the UTRAN, the P2Pcommunicating UEs and other conventional UEs allocated in the sametimeslot can overhear the information transferred on the FORWARD link orBACKWARD link, i.e.: P2P communication changes the UP-UTRAN-DOWN mode inconventional TD-SCDMA systems. From the view of the UTRAN, even thoughthe UEs have no connection with the UTRAN, the FORWARD link and BACKWARDlink are associated with a certain uplink timeslot and/or downlinktimeslot (the FORWARD link and BACKWARD link can correspond to differentuplink timeslot and/or downlink timeslot depending on different resourceallocation schemes). Hence, P2P communication will cause signalinterference to conventional communication. Similarly, two P2Pcommunicating UEs can also overhear the information transferred in theuplink timeslot or downlink timeslot associated with their FORWARD linkor BACKWARD link during P2P communication. Therefore, when conventionallinks share the same timeslots with P2P link, conventional uplink ordownlink communication will interfere with the P2P FORWARD link orBACKWARD link communication, which seriously deteriorates theperformance of P2P-enabled TDD CDMA communication systems.

To improve the performance of P2P-enabled TDD CDMA communicationsystems, it's necessary to effectively reduce the signal interferencecaused by introducing P2P communication mode to the TD-SCDMAcommunication systems.

First of all, an analysis will go to the interference signals brought byintroducing P2P communication mode in the following, and then how toreduce interference signals will be described. For simplicity, thetimeslot in which one UE transmits signals to the other UE through theabove FORWARD link or BACKWARD link is called transmit timeslot (Txtimeslot), while the timeslot in which the UE receives signals fromanother UE through the above FORWARD link or BACKWARD link is calledreceive timeslot (Rx timeslot), wherein the Tx timeslot and the Rxtimeslot are respectively associated with an uplink timeslot and/ordownlink timeslot in the sub-frame in conventional communication.

1. Interference Associated with Uplink Timeslot Between P2P Link andConventional Link

FIG. 3 illustrates the interferences between P2P link and conventionallink in P2P-enabled TD-SCDMA systems when the P2P link is associatedwith uplink timeslot. As shown in FIG. 3, it is assumed that UE1 and UE2work in P2P mode and UE3 works in conventional mode, wherein UE1's Txtimeslot is associated with UE3's uplink timeslot, that is, UE1 and UE3are allocated in the same uplink timeslot to transmit signalsrespectively to UE2 and the UTRAN. S1 is the information from UE1 to UE2through direct link (taken as FORWARD link) and S2 is uplink informationtransmitted to the UTRAN via uplink from UE3, moreover, both S1 and S2are associated with the same uplink timeslot but with differentspreading codes.

In TD-SCDMA communication systems, one of the most important features isto maintain uplink synchronization, which means signals from differentUEs should arrive at the UTRAN at the same time to guarantee theorthogonality of the spreading codes of signals from the main paths ofdifferent UEs. In this way, the system performance can be improvedgreatly by some advanced receiver algorithms and the computationalcomplexity for the algorithms can be reduced greatly.

For conventional communication systems, the UTRAN is involved in everyproceeding communication procedure as information source, destination orrelayer, so it can monitor and control the UE' uplink transmitting timeaccording to a specific traffic burst structure in CONNECT mode, andthus maintain uplink synchronization for each UE. But for P2Pcommunication mode, the UTRAN is only involved in link establishmentprocedure and not involved in the P2P communication procedureafterwards. Therefore, during P2P communication, there is no dedicatedchannel between the UTRAN and the two P2P UEs, and the UTRAN can'tadjust the synchronization advance of the two P2P UEs transmittingsignals by using specific traffic burst to maintain uplinksynchronization even if it can overhear and estimate the uplinksynchronization shift of the two P2P UEs.

Referring to FIG. 3, when UE1 and UE3 transmit signals in the sameuplink timeslot, the UTRAN can overhear information S1 transferred fromUE1 to UE2 (to the UTRAN, S1 is considered as interference signal I1).But as described above, there is no dedicated channel between the UTRANand UE1, so the UTRAN can't adjust UE1's transmission time by using thetraffic burst in conventional communication mode even if it can overhearinformation S1 and estimate UE1's synchronization shift information,which means UE1 working in P2P mode may lose uplink synchronization withthe UTRAN (UE3 working in conventional mode can maintain uplinksynchronization with the UTRAN in conventional way). In another word, I1and S2 are likely to arrive at the UTRAN unsynchronously, which willpotentially impair uplink synchronization and thus degrade the systemperformance.

Similarly, when UE1 and UE3 transmit signals in the same allocateduplink timeslot, UE2 can also overhear signal S2 transferred from UE3 tothe UTRAN (to UE2, S2 is considered as interference I2), andinterference signal I2 will also produce impact on UE2 to receive S1,which may potentially impair the P2P communication quality.

2. Interference Associated with Downlink Timeslot Between P2P Link andConventional Link

FIG. 4 illustrates the interferences between P2P link and conventionallink in a P2P-enabled TD-SCDMA system when the P2P link is associatedwith downlink timeslot. As shown in FIG. 4, it is assumed that UE1 andUE2 work in P2P mode and UE3 works in conventional mode, wherein UE1'sRx timeslot is associated with UE3's downlink timeslot, that is, UE1 andUE3 are allocated in the same downlink timeslot to respectively receivesignals from UE2 and the UTRAN. S3 is the P2P link information from UE2to UE1 via direct link (taken as BACKWARD link) and S4 is downlinkinformation from the UTRAN to UE3 via downlink, furthermore, both S3 andS4 are associated with the same downlink timeslot but with differentspreading codes.

In FIG. 4, the downlink information S4 transmitted from the UTRAN to UE3may produce interference to other UEs who share the same downlinktimeslot with UE3 but use different spreading codes to receive signals.Such interference is called multi-access interference (MAI).

Referring to FIG. 4, when UE1 and UE3 are allocated in the same downlinktimeslot to receive signals, UE1 can overhear information S4 transferredfrom the UTRAN to UE3 via downlink (to UE1, S4 is considered asinterference signal I4), and generally the transmission power of signalsfrom the UTRAN is relatively strong, so interference signal 14 is likelyto impair the direct communication quality seriously.

Similarly, when UE1 and UE3 are allocated in the same downlink timeslotto receive signals, UE3 can also overhear information S3 transferredfrom UE2 to UE1 (to UE3, S3 is considered as interference signal I3, andmeanwhile UE2 can be taken as the pseudo-UTRAN), and the interferencesignal I3 will impair the communication quality of UE3 near UE2 andother UEs in the same timeslot to receive signals as UE3.

3. Interference Between P2P Direct Link Pairs

FIG. 5 illustrates the interferences between two P2P direct link pairsin a P2P-enabled TD-SCDMA system, wherein a UE in one of the two P2Plink pairs receives or transmits signals to the UE in another P2P linkpair. Assume that UE1 and UE2 work in one P2P link pair while UE3 andUE4 in another P2P link pair.

Because P2P link pairs are symmetrical, signal S5 or S6 from UE1 to UE2will become interference I5 or I6 to UE4 who is receiving signals fromUE3 in associated timeslot. Obviously interference I5 or I6 may alsogreatly impair the direct communication quality.

As noted above, after P2P link is introduced in conventional TD-SCDMAsystems, there exist 6 possible interference signals I1, I2, I3, I4, I5and I6. Depending on whether the UTRAN is involved, the above 6interference signals can be divided into two types. The first typeincludes interferences between the UEs, such as I2, I3, I5, and I6; andthe second type includes interferences with UTRAN involved, such as I1and I4.

To guarantee the communication quality of a P2P-enabled TD-SCDMAcommunication system, effective methods needs to be researched to cancelthe above 6 interferences (it's better to achieve that without changingthe physical layer structures of existing communication systems).

Regarding to interference signal I1 of the first type, two methods andapparatuses for canceling interference signal I1, are respectivelyelaborately described in the patent application document entitled “AMethod and Apparatus for Uplink Synchronization Maintenance with P2PCommunication in Wireless Communication Networks”, filed by KONINKLIJKEPHILIPS ELECTRONICS N.V. on Mar. 7, 2003, application Ser. No.03119894.5, and another co-pending patent application document entitled“A Method and Apparatus for Uplink Synchronization Maintenance with P2PCommunication in Wireless Communication Networks”, filed by KONINKLIJKEPHILIPS ELECTRONICS N.V. application Ser. No. 10/547,586and incorporatedherein as reference.

As for interference signal I4 of the first type, a method and apparatusfor canceling interference signal I4, is elaborately described in thepatent application document entitled “A Method and Apparatus forSupporting P2P Communication in TDD CDMA Communication Systems”, filedby KONINKLIJKE PHILIPS ELECTRONICS N.V. on Apr. 14, 2003, applicationSer. No. 03110415.0, and incorporated herein as reference.

As for interference signals I2, I3, I5 and I6 of the second type,collectively called Iaj, they can be reduced or cancelled by effectivelylimiting the radio range supported by P2P communication and adoptingintelligent radio resource control scheme. Considering the limited P2Pradio range, this invention proposes a scheme for canceling interferencesignal Iaj. This scheme can reduce interference signal Iaj by obtainingthe mutual interference situation between a P2P UE and other UEs in thesame cell (for example through position information) and allocatingdifferent timeslots to the P2P UE and its adjacent UEs.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method and apparatusfor supporting P2P communication in TDD CDMA communication systems, soas to reduce interferences caused by introducing P2P communication modeinto TDD CDMA communication systems.

To achieve the above object, a method is proposed for cancelinginterference signals caused by introducing P2P (Peer to Peer)communication, performed by a network system in wireless communicationsystems in accordance with the present invention, comprising: (i)receiving a call request from a UE for communicating in UP-UTRAN-DOWNmode in a cell; (ii) judging whether there is at least one suitable linktimeslot in the several available timeslots for the UE to avoid beinginterfered by P2P signals transmitted by the said chosen UEs allocatedin the suitable timeslot when the UE communicates in the suitabletimeslot, according to the relative position of the UE and chosen P2Pcommunicating UEs in the cell; (iii) approving the call request from theUE and allocating the suitable timeslot to the UE if the suitabletimeslot is available.

To achieve the above object, another method is proposed for cancelinginterference signals caused by introducing P2P (Peer to Peer)communication, performed by a network system in wireless communicationsystems in accordance with the present invention, comprising: (I)receiving a call request for communicating in P2P communication modewith the other UE from a UE in a cell; (II) judging whether there are atleast two suitable timeslots in the several available timeslots for theUE and the other UE to avoid producing interference of P2P signals tochosen UEs already allocated with radio resources in the suitabletimeslots, when the UE and the other UE are communicating in P2P mode inthe suitable timeslots, according to the relative position of the UE andthe other UE and said chosen UEs already allocated with radio resourcesin the cell; (III) approving the call request from the UE and allocatingsaid suitable timeslots to the UE and the other UE if there exist saidsuitable timeslots.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 is a schematic diagram illustrating conventional communicationmode in which two UEs communicate through the relaying of base stations;

FIG. 2 is a schematic diagram illustrating the P2P communication betweentwo UEs;

FIG. 3 is a schematic diagram illustrating the generation ofinterference signals between direct link and conventional link employinguplink timeslot to communicate in a P2P-enabled TD-SCDMA system;

FIG. 4 is a schematic diagram illustrating the generation ofinterference signals between direct link and conventional link employingdownlink timeslot to communicate in a P2P-enabled TD-SCDMA system;

FIG. 5 is a schematic diagram illustrating the generation ofinterference signals between two direct link pairs in a P2P-enabledTD-SCDMA system;

FIG. 6 is a schematic diagram illustrating timeslot allocation inaccordance with the first method of the present invention;

FIG. 7 is a schematic diagram illustrating timeslot allocation inaccordance with the second method of the present invention;

FIG. 8 is a flow chart illustrating resource allocation in accordancewith the second method of the present invention;

FIG. 9 is a flow char illustrating resource allocation in FIG. 8 when aUE employing conventional communication mode joins;

FIG. 10 is a flow char illustrating the resource allocation in FIG. 8when a UE employing P2P communication mode joins;

DETAILED DESCRIPTION OF THE INVENTION

According to the above analysis of interference signals in a P2P-enabledTD-SCDMA communication system, the present invention primarily focuseson reducing interference signal Iaj, that is, the problem ofinterference signals between UEs after P2P communication mode isintroduced.

Iaj exists between a P2P UE and other UEs that are allocated in the samecell and within the radio range of the P2P UE. To reduce interferencesignal Iaj, the range between these UEs can be increased so that otherUEs allocated in the same timeslot as the P2P UE go out of the radiorange of the P2P UE and thus avoid being interfered by P2P signals. Butit is often very difficult to control the distance between two UEswithin a certain range in practical communications due to therandomicity of communication time and location. So, for UEs who fallswithin a certain range, it can be a more effective solution to reduceinterference signal Iaj by allocating different timeslots.

A detailed description will be given below to the method provided in thepresent invention for reducing interference signal Iaj in conjunctionwith accompanying drawings, taking TD-SCDMA system as an example.

FIG. 6 illustrates the timeslot allocation map for reducing interferencesignal Iaj by adopting the first method in the present invention. In theexample shown in FIG. 6, there are a pair of P2P UEs P1 and P2, and fourUEs employing conventional UP-UTRAN-DOWN communication mode UEa, UEb,UEc and UEd. The timeslot allocation is shown in FIG. 6. In a sub-framecomposed of 6400 chips and with time length as 5 ms, Ts0 is for downlinkcommon traffic, Ts1 for P2P UE's forward traffic (P1 transmit, P2receive), Ts2 for P2P UE's backward traffic (P2 transmit, P1 receive),Ts3 for uplink traffic of CDMA mode based UEa, UEb, UEc and UEd whoemploy conventional UP-UTRAN-DOWN communication mode, Ts4 for downlinktraffic of UEa employing conventional communication mode, Ts5 fordownlink traffic of UEb employing conventional communication mode, andTs6 for downlink traffic of CDMA-based UEc and UEd who employconventional communication mode. In the method shown in FIG. 6, theessence of the method is: for two timeslots occupied by a pair of P2PUEs, such as Ts1 and Ts2 in FIG. 6, no other pair of P2P UEs and otherUEs employing conventional communication mode are allocated in. That is,the timeslots occupied by forward link and backward link of P2P link,are occupied exclusively by two P2P communicating UEs.

The timeslot allocation method as shown in FIG. 6, is easy to beimplemented. But the timeslots occupied by P2P UEs can't be shared withother UEs by adopting CDMA mode, so the whole system has actually beenchanged into a communication mode with pure TDMA, which greatly reducescapacity of the communication system. Therefore, a more intelligenttimeslot allocation method is needed to reduce interference Iaj betweenUEs allocated in a same timeslot, as well as continue to use CDMA mode,and thus enlarge system capacity effectively.

FIG. 7 illustrates the timeslot allocation map for reducing interferencesignal Iaj by adopting the second method in the present invention. Inthe second method, a P2P UE can share a timeslot with other UEs by CDMAmode, but it should be guaranteed that no radio signal interference willbe produced between the P2P UE and other UEs allocated in the sametimeslot, otherwise the sharing can't be achieved. To put it moreclearly, if the P2P UB Py can share a timeslot by CDMA mode with UEx whocan be a UE in conventional communication mode or a UE employing P2Pcommunication mode, when one of Py and UEx is transmitting signals whilethe other is receiving signals, the UE that is transmitting signalswon't produce interference to the other UE that is receiving signals toreceive signals correctly. That is, in this timeslot, if Py is in Txstate and UEx in Rx state, UEx won't be interfered by Py when receivingsignals; similarly, in this timeslot, if UEx is in Tx state and Py in Rxstate, Py won't be interfered by UEx when receiving signals.

In summary, the essence of the second method in the present inventionlies in that: if a UE falls within the radio range of another P2P UE,they have to be allocated in different timeslots in order to reduceinterference Iaj caused by P2P communication; if a UE is far away fromanother P2P UE, on condition that it won't be interfered by the P2P UE,the two UEs can share a same timeslot by CDMA mode (i.e.: one UE is inTx state while the other is in Rx state), thus to enhance systemcapacity.

According to the timeslot allocation requirement in the second method,when a UE camping in the cell sends a call request (the request can beone for communicating in P2P mode or one for communicating inconventional UP-UTRAN-DOWN mode) to the base station, the base stationsystem sends a paging message to the called UE depending on theinformation about the called UE contained in the request, and receivesan ACK message from the called UE afterwards. During this process, thebase station system can obtain the position information about thecalling UE and the called UE according to the information included inthe call request and the ACK message; and also can test the calling UEand the called UE, and obtain the position information about the callingUE and the called UE according to the information from the calling UEand the called UE.

Then, the base station system calculates the distance between each P2Pcommunicating UE and other communicating UEs according to the positioninformation of each UE, to determine whether the distance exceeds theradio range for the P2P UE to send P2P signals. If it's determined thatthe distance exceeds the P2P radio range, the UE and the P2P UE canshare a same timeslot to perform their respective communication. If thedistance doesn't exceed the P2P radio range, the UE and the P2P UE haveto be allocated in different timeslots to perform their respectivecommunication.

Obviously, the timeslot allocation in the second method is morecomplicated than that in the first method. But with the second method, aP2P UE and another UE between which the distance exceeds the P2P radiorange, can utilize a same timeslot to perform their respectivecommunication by adopting CDMA mode. So radio systems adopting thesecond method to allocate timeslots can achieve remarkably greatercapacity than those adopting the first method.

In the above second method as described, a UE can be classified into twosets according to whether the distance between the UE and a P2P UE Piexceeds the radio range of the P2P UE. If the distance between the twoUEs exceeds the radio range of the P2P UE, the UE belongs to UEs notsuffering from P2P interference and can be categorized in the sharableset Ypi that can share the same timeslot with Pi. Otherwise, the UEbelongs to UEs suffering from the P2P interference and should becategorized in the unshared set Xpi that can't share the same timeslotwith Pi. Of course, both Xpi and Ypi don't include another P2P UEP_(i+1) that is performing P2P communication with P_(i).

FIG. 7 illustrates the timeslot allocation in a TD-SCDMA sub-frame,wherein, each timeslot include UEs without P2P interference and UEs withP2P interference, according to the requirement of the above secondmethod. As FIG. 7 shows, in a sub-frame composed of 6400 chips and withtime length as 5 ms, assume that there exist only a pair of P2P UEs P1and P2, four conventional UEs UEa, UEb, UEc and UEd, moreover,X_(P1)={UEa}, Y_(P1)={UEb, UEc, UEd}, X_(P2)={UEa, UEb } andY_(P2)={UEc, UEd}. The timeslots can be allocated as: Ts5 for P1 totransmit, P2 to receive and UEb to downlink receive; Ts6 for P1 toreceive, P2 to transmit and UEc and UEd to downlink receive; Ts4 for UEato downlink receive; Ts0 for downlink common traffic; Ts1 for UEa andUEb's uplink traffic; Ts2 for UEc's uplink traffic; and Ts3 for UEd'suplink traffic.

In the following, further description will be given to the timeslotallocation in the above second method by taking FIG. 4 as example. Asdescribed above, in FIG. 4, UE1 and UE2 are a pair of P2P UEscommunicating in P2P mode, while UE3 is a conventional UE communicatingin conventional mode. The base station system calculates whether thedistance between UE2 and UE3 exceeds the radio range for UE2 to transmitP2P signals, according to the position information about UE2 and UE3. Ifthe distance between UE2 and UE3 exceeds the radio range for UE2 totransmit P2P signals, UE1 and UE3 can be allocated in a same timeslot torespectively receive information S3 from UE2 and information S4 from thebase station system. Signals transmitted by UE2 can't arrive at UE3, soUE3 can avoid being interfered by the P2P signal I3 from UE2.

In similar ways, interference signals I2, I5 and I6 in FIG. 3 and FIG. 5can all be cancelled according to the timeslot allocation requirement inthe second method, so as to guarantee the communication quality of aTD-SCDMA system that introduces P2P communication mode.

A detailed description will be given below to the above second method,in conjunction with FIG. 8, 9 and 10, wherein D is the threshold of theradio range that can be reached by P2P interference signals. When thedistance between a P2P UE and another UE exceeds D, they can beallocated in a same timeslot, otherwise they can't be allocated in asame timeslot. The allocation of timeslots can be done once to bereallocated through performing intelligent resource control scheme bythe base station system every certain time period Tp whose value can beset according to specific requirement of the network system.

As FIG. 8 shows, first, the base station system acquires the currentresource allocation status in the cell, including the positioninformation of all communicating UEs in the cell (step S1), the pairnumber Np of P2P communicating UEs in the cell and the synchronizationmode (step S2), and the number Nn of current proceeding conventional UEsin the cell (step S3). Wherein: (i) the position information about a UEcan be included the UE's report to the base station or the basestation's measurement; (ii) the base station system can distinguishwhether UEs in the cell are in P2P communication mode or in conventionalcommunication mode, and restore the information of the UEs in P2Pcommunication mode; (iii) the synchronization mode of each P2P UE alsoneeds to be acquired when the pair number Np of P2P UEs is acquired,because the occupation of uplink timeslot/downlink timeslot in P2Pcommunication can be known only after the synchronization mode of eachP2P UE is acquired .

Then, check whether there is a new call request for communicating inconventional UP-UTRAN-DOWN mode from a conventional UE since theintelligent resource control scheme is executed last time (step S4). Ifthere is such a call request, calculate whether there is at least onesuitable link timeslot in the several available timeslots according tothe position information of the UE, wherein the link timeslot can be anuplink timeslot or a downlink timeslot and the suitable timeslot canstill satisfy the communication requirement of the communication networkafter being allocated to the UE, i.e.: when the UE communicates inconventional mode in said suitable timeslot, it won't be interfered byother P2P communicating UEs in the cell (step S5). This step will bedescribed in detail later in conjunction with FIG. 9. If such a suitabletimeslot doesn't exist, reject the new call request from theconventional UE (step S7). If such a suitable timeslot exists, the newcall request from the conventional UE will be approved (step S6). Forevery call request from conventional UEs, iterate the above steps S4 toS7, to approve every conventional call request satisfying therequirement.

After the conventional call request is processed, check whether there isa new call request for communicating in P2P mode from a UE since theintelligent resource control scheme is implemented last time (step S8).If there is such a call request, calculate whether there are at leasttwo suitable timeslots (can be two uplink timeslots or two downlinktimeslots or an uplink timeslot and a downlink timeslot) in the severalavailable timeslots, according to the position information about the UEand the other UE (namely the called) involved in P2P communication,wherein the two suitable timeslots can still satisfy the uplink and/ordownlink communication requirement of the communication network afterbeing reallocated to the two UEs. That is, when the UE performs P2Pcommunication with the called UE, it won't produce P2P interference toother communicating UEs and other UEs already allocated radio resource(e.g. the above UE whose conventional call request has just beenapproved) (step S9). This step will be described below in detail inconjunction with FIG. 10. If such suitable timeslots don't exist, rejectthe new P2P call request from the UE (step S10). If such suitabletimeslots exist, the new P2P call request from the UE will be approved(step S11). For every new P2P call request from the UE, iterate theabove steps S8 to S11, to approve every P2P call request satisfying therequirement.

After processing the conventional call request and P2P call request,reallocate uplink and downlink timeslots for conventional UEs and twoP2P UEs involved in each P2P communication in the cell according toevery conventional call request and every P2P call request approvedthrough the above steps, so that each UE can perform conventional and/orP2P communication in the allocated suitable timeslot (step S12).

After the communication resource is reallocated with the aboveintelligent resource control scheme, enter into a waiting state. Whenthe radio resource reallocation timer reaches the time period Tp ofchannel allocation, reset the radio resource reallocation timer firstlyand restart to time, and then iterate procedures in the above steps S1to S12 (step S13).

In FIG. 9, it is described in detail that said suitable timeslot can bedetermined through computation according to the position informationabout the UE as above step S5, so that the uplink and downlinkcommunication requirement of the communication network can be satisfiedwhen the UE is allocated to communicate in said suitable timeslot. Morespecifically as follows:

First, acquire the position information about the UE sending theconventional call request, wherein the position information can beincluded in the UE's report to the base station, or acquired from theinformation from UE by the base station system's measurement (step S20).

Then, beginning from the first communicating P2P UE (step S21),calculate the distance between the UE sending conventional call request(called as conventional requesting UE later) and each other P2Pcommunicating UE in the cell respectively (or just calculate thedistance between the conventional requesting UE and a part of chosen P2PUEs, wherein the chosen P2P UEs are those communicating with theconventional requesting UE and falling within a certain range). If thedistance between conventional requesting UE and a P2P UE exceedsthreshold D, mark the conventional requesting UE as one capable ofsharing a same timeslot with the P2P UE, that is, categorize theconventional requesting UE into the sharable set of the P2P UE.Otherwise, mark the conventional requesting UE as one incapable ofsharing a same timeslot with the P2P UE, that is, categorize theconventional requesting UE into the unshared set of the P2P UE (stepS22).

Execute the above marking procedure to each P2P communicating UE in thecell (step S23). After executing the above marking procedure to all P2Pcommunicating UEs in the cell (step S24), taking into account of thechannel sharing principle of the above conventional requesting UE andall existing P2P UEs, check whether the radio channel resource such asthe reallocated timeslots and codes and the like can still satisfy theuplink and downlink communication requirement, after reconfiguringsystem if the conventional communication is added. That is, regarding toone or more uplink timeslots and one or more downlink timeslots in theseveral available timeslots, the UE can share these timeslots with otherP2P UEs previously allocated in these timeslots when these timeslots areallocated to the conventional requesting UE (step S25).

In FIG. 10, it is described in detail that said suitable timeslots canbe determined through computation according to the position informationabout the UE as above step S9, so that the uplink and downlinkcommunication requirement of the communication network can be satisfiedwhen the UE is allocated to communicate in said suitable timeslots. Morespecifically as follows: First, acquire the position information aboutthe UE sending the P2P call request (called as P2P request UB later) andanother UE involved in P2P communication. The position information canbe included in the information of the UE and the P2P called UE's reportto the base station, or acquired from the information from the P2Pcommunication called UE by the base station system's measurement (stepS30).

Then, beginning from the first UE already allocated radio resource inthe cell (step S31), calculate the distance between the P2P requestingUE and each of other UEs already allocated radio resource in the samecell respectively. These other UEs include: each communicating UE in thecell, and new conventional UEs whose conventional call requests havejust been approved through steps S4˜S6 in the above FIG. 8. (the totalnumber of the newly approved conventional UEs is denoted as Nm). (Orjust calculate the distance between the P2P requesting UE and a part ofchosen UEs, wherein the chosen UEs are those having been allocated radioresource and falling within the radio range of the P2P requesting UE).If the distance between the P2P requesting UE and any of the above UEsexceeds threshold D, mark this UE as one capable of sharing a sametimeslot with the P2P requesting UE, otherwise mark it as one incapableof sharing a same timeslot with the P2P requesting UE (step S32).

Execute the above marking procedure to each UE already allocated radioresource in the cell (step S33). After executing the above markingprocedure to all UBs already allocated radio resource in the cell (stepS34), beginning from the first UE allocated radio resource in the cell(step S35), calculate the distance between the called UE involved in theP2P call request and other UEs already allocated radio resource in thesame cell respectively. These other UEs include: each communicating UEin the cell, and new conventional UEs whose conventional call requestshave just been approved through steps S4˜S6 in the above FIG. 8. (thetotal number of the newly approved conventional UEs is still denoted byNm). (Or just calculate the distance between the called UE and a part ofchosen UEs, wherein the chosen UEs are those having been allocated radioresource and falling within the radio range of the calling UE. )If thedistance between the P2P called UE and any of the above UEs exceedsthreshold D, mark this UE as one capable of sharing a same timeslot withthe P2P called UE, otherwise, mark it as one incapable of sharing a sametimeslot with the P2P called UE (step S36). Execute the above markingprocedure to each UB already allocated radio resource in the cell (stepS37). After executing the above marking procedure to all UEs alreadyallocated radio resource in the cell (step S38), taking into account ofthe channel sharing principle of the above P2P requesting UE, the P2Pcalled UE and all existing UEs, check whether the radio channel resourcesuch as the reallocated timeslots and codes and the like can stillsatisfy the uplink and/or downlink communication requirement afterreconfiguring system if the P2P call request is added. That is, at leasttwo timeslots in the several available timeslots, the P2P requesting UEand the P2P called UE can share the two timeslots with other UEspreviously allocated in the timeslots when the two timeslots areallocated to the P2P requesting UE and the P2P called UE (step S39).

The above method for supporting P2P communication in TID-SCDMA systemsin accordance with the present invention as described in conjunctionwith FIGS. 8, 9 and 10, can be implemented in computer software, orhardware, or in combination of software and hardware.

BENEFICIAL RESULTS OF THE INVENTION

As described above, in the method and apparatus for supporting P2Pcommunication in TD-SCDMA systems provided in the present invention,only those UEs whose distances to P2P UE exceed the P2P radio range ofthe P2P UE, can be allocated in the same timeslot as the P2P UE, sothese UEs sharing a same timeslot can perform their respectivecommunication, without being interfered by transferring P2P signals.

Although the method and apparatus for supporting P2P communication inTD-SCDMA systems provided in the invention has been shown and describedwith respect to exemplary embodiments of TD-SCDMA, it should beunderstood by those skilled in the art that the communication method andapparatus are not limited hereof, but also suitable to other TDD CDMAsystems.

It is also to be understood by those skilled in the art that the methodand apparatus for supporting P2P communication in TD-SCDMA systemsdisclosed in this invention can be modified considerably withoutdeparting from the spirit and scope of the invention as defined by theappended claims.

1. A method for canceling interference signals brought by introducingP2P (Peer to Peer) communication in wireless communication systems,performed by a network system, comprising: (i) receiving a call requestfrom a user equipment in a cell for communicating in UP-UTRAN-DOWN mode,wherein the requesting user equipment is hereinafter referred to as therequesting UE; (ii) judging whether there is an appropriate linktimeslot, for which the requesting UE can share a same timeslot with aP2P user equipment allocated with radio resources in the cell, fromamong several available timeslots for the requesting UE to avoid beinginterfered by P2P signals transmitted by P2P communicating userequipments allocated with radio resources in a corresponding appropriateshared timeslot when the requesting UE communicates in the appropriateshared timeslot, according to the relative position of the requesting UEand the P2P communicating user equipments in P2P communication in thecell; and (iii) approving the call request from the requesting UE andallocating the appropriate shared timeslot to the requesting UE if theappropriate timeslot is available for sharing.
 2. The method accordingto claim 1, wherein step (ii) includes: (a) computing the distancebetween the requesting UE and the P2P communicating user equipments,according to the position information of the requesting UE and the P2Pcommunicating user equipments; and (b) allocating the shared timeslot tothe requesting UE as an appropriate shared timeslot, if the distancebetween the P2P communicating user equipments and the requesting UEallocated in the shared timeslot exceeds a predefined threshold, withregard to at least one timeslot to be shared from among said severalavailable timeslots.
 3. The method according to claim 1, wherein the P2Pcommunicating user equipments at least include those P2P communicatinguser equipments in P2P communication in the cell, whose proximity to therequesting UE introduces an interference signal.
 4. The method accordingto claim 3, wherein the call request from the user equipment will berejected if it's determined in step (ii) that there is no saidappropriate timeslot in said several available timeslots for which therequesting UE can share a same timeslot with one of the P2Pcommunicating user equipment allocated with radio resources in the cell.5. A method for canceling interference signals brought by introducingP2P (Peer to Peer) communication in wireless communication systems,performed by the network system, comprising: (I) receiving a callrequest from a user equipment in a cell for communicating with anotheruser equipment in P2P communication mode in the cell, wherein therequesting user equipment is hereinafter referred to as the requestingP2P UE and the another user equipment is hereinafter referred to as theother P2P user equipment (II) judging whether there are at least twoappropriate link timeslots for which each of the requesting P2P UE andthe other P2P user equipment can share one of at least two appropriatetimeslots with each other or with user equipments allocated with radioresources in the cell, from among several available timeslots for therequesting P2P UE and the other P2P user equipment to avoid producinginterference of P2P signals to user equipments allocated with radioresources in corresponding appropriate shared timeslots, when therequesting P2P UE and the other P2P user equipment communicating in P2Pmode share in the appropriate timeslots, according to the relativeposition of the a) requesting P2P user equipment and the other P2P userequipment and b) the user equipments allocated with radio resources, and(III) approving the call request from the requesting P2P user equipmentand allocating said appropriate shared timeslots to the requesting P2Puser equipment and the other P2P user equipment if there are appropriatetimeslots available for sharing.
 6. The method according to claim 5,step (II) comprising: (A) computing (i) the distances between therequesting P2P user equipment and the user equipments allocated withradio resources in the cell and (ii) the distances between the other P2Puser equipment and the user equipments allocated with radio resources inthe cell respectively, according to position information of therequesting P2P user equipment and the other P2P user equipment and thatof user equipments allocated with radio resources in the cell; (B)allocating the two timeslots to the requesting P2P user equipment andthe other P2P user equipment as the appropriate shared timeslots, if thedistances between the user equipment allocated with radio resources inrespective ones of the two timeslots and the requesting P2P userequipment and the other P2P user equipment exceed a certain threshold,with regard to at least two timeslots to be shared from among saidseveral available timeslots.
 7. The method according to claim 5, whereinthe user equipments allocated with radio resources in the cell at leastinclude those user equipments allocated with radio resources, whoseproximity to the requesting P2P user equipment and said other P2Pequipment introduces an interference signal.
 8. The method according toclaim 7, wherein the call request for P2P communication from the userequipment will be rejected if there are no said appropriate timeslots insaid several available timeslots in step (II) for which the requestingP2P UE can share a same timeslot with one of the user equipmentallocated with radio resources in the cell.
 9. A method for cancelinginterference signals brought by introducing P2P (Peer to Peer)communication in wireless communication systems, performed by thenetwork system, comprising: receiving a call request from a userequipment in a cell, hereinafter referred to as the requesting P2P UEfor communicating with another user equipment in P2P communication mode;judging whether P2P communication can be established between therequesting P2P user equipment and the other user equipment, according toinformation of the requesting P2P user equipment and the other userequipment; allocating the requesting P2P user equipment and the otheruser equipment with shared timeslots for forward link and backward link,wherein the shared timeslots occupied respectively by (i) the forwardlink of the requesting P2P UE and backward link of the other userequipment and (ii) the backward link of the requesting P2P UE andforward link of the other user equipment, are exclusively occupied bythe requesting P2P user equipment and the other user equipment, if therequirement for P2P communication establishment can be satisfied.
 10. Anetwork system for canceling interference signals brought by introducingP2P communication in wireless communication systems, comprising: areceiving means, for receiving a call request from a user equipment in acell for communicating in UP-UTRAN-DOWN mode, wherein the requestinguser equipment is hereinafter referred to as the requesting UE; ajudging means, for judging whether there is an appropriate link timeslotfor which the requesting UE can share a same timeslot with a P2P userequipment allocated with radio resources in the cell, from among severalavailable timeslots for the requesting UE to avoid being interfered byP2P signals transmitted by P2P communicating user equipments allocatedwith radio resources in a corresponding appropriate shared timeslot whenthe requesting UE communicates in the appropriate shared timeslot,according to the relative position of the requesting UE and the P2Pcommunicating user equipments communicating in P2P communication mode inthe cell; and an approving means, for approving the call request fromthe requesting user equipment when there is an appropriate sharedtimeslot and allocating the appropriate shared timeslot to therequesting user equipment.
 11. The network system according to claim 10,wherein said judging means comprises: a computing means, for computingthe distance between the requesting user equipment and the P2Pcommunicating user equipments, according to the position information ofthe requesting user equipment and the P2P communicating user equipments;an allocating means, for allocating the shared timeslot to therequesting user equipment as an appropriate shared timeslot, when thedistance between the P2P communicating user equipments allocated in theshared timeslot and the requesting P2P user equipment exceeds apredefined threshold, with regard to at least one timeslot to be sharedfrom among several available time slots.
 12. The network systemaccording to claim 10, wherein P2P communicating user equipments atleast include those P2P communicating user equipments in P2Pcommunication with the requesting user equipment, whose proximity to therequesting user equipment introduces an interference signal.
 13. Anetwork system for canceling interference signals brought by introducingP2P communication in wireless communication systems, comprising: areceiving means, for receiving call request from a user equipment in acell for communicating with another user equipment in P2P communicationmode in the cell, wherein the requesting user equipment is hereinafterreferred to as the requesting P2P UE and the another user equipment ishereinafter referred to as the other P2P user equipment; a judgingmeans, for judging whether there are at least two appropriate linktimeslots for which each of the requesting P2P UE and the other P2P userequipment can share one of at least two appropriate timeslots with eachother or with user equipments allocated with radio resources in thecell, from among several available timeslots for the requesting P2P userequipment and the other P2P user equipment in P2P communication in theappropriate shared timeslots to avoid producing interference of P2Psignals to user equipments allocated with radio resources in thecorresponding appropriate shared timeslots, according to the relativeposition of the a) requesting P2P user equipment and the other P2P userequipment and chosen b) the user equipments allocated with radioresources in the cell; an approving means, for approving the callrequest from the requesting P2P user equipment when there areappropriate timeslots available for sharing and allocating theappropriate shared timeslots to the requesting P2P user equipment andthe other P2P user equipment.
 14. The network system according to claim13, wherein said judging means comprises: a computing means, forcomputing the respective distances between the requesting P2P userequipment and the other P2P user equipment and the user equipmentsallocated with radio resources in the cell, according to positioninformation of the requesting P2P user equipment and the other P2P userequipment and that of the user equipments allocated with radio resourcesin the cell; and an allocating means, for allocating the requesting P2Puser equipment and the other P2P user equipment with the two timeslotsas appropriate shared timeslots, if the distances between the userequipments allocated with radio resources in respective ones of the twotimeslots and the requesting P2P user equipment and the other P2P userequipment exceed a certain threshold, with regard to at least twotimeslots to be shared from among said several available timeslots. 15.The network system according to claim 13, wherein the user equipmentsallocated with radio resources in the cell at least include those userequipments allocated with radio resources, whose proximity to therequesting P2P user equipment introduces an interference signal.
 16. Anetwork system for canceling interference signals brought by introducingP2P (Peer to Peer) communication in wireless communication systems,comprising: a receiving means, for receiving call request from a userequipment in a cell, hereinafter referred to as the requesting P2P UE,for communicating another user equipment in P2P communication mode; ajudging means, for judging whether P2P communication between therequesting P2P user equipment and the other user equipment can beestablished, according to information of the requesting P2P userequipment and the other user equipment; an allocating means, forallocating the requesting P2P user equipment and the other userequipment with shared timeslots for forward link and backward link,wherein the shared timeslots respectively occupied by (i) the forwardlink of the requesting P2P UE and backward link of the other userequipment and (ii) the backward link of the requesting P2P UE andforward link of the other user equipment, are exclusively occupied bythe requesting P2P user equipment and the other user equipment, if therequirement for establishing P2P communication can be satisfied.